Amplifier for talking machines



Apr. 3, 1923. 1,450,241

J. F. BIGGS v AMPLIFIER FOR 'TALKING MACHINES Filed Aug. 12 1920 2 sheets-sheet 1 'INVENTOR.

ATTORNEY.

Apr. 3, 1923.

1,450,241 J. F. BIGGS AMPLIFIER FOR TALKING MACHINES Filed Aug. 12, 1920 2 sheets-sheet 2 INVENTOR. d. 1 5/6 65 BY -II I I I A TTORNE Y.

Patented Apr. 3, 1923.

JOSEPH F. n rses, or RICHMOND, VIRGINIA.

AMPLIFIER FOR TALKING MACHINES.

Application filed August 12, 1920. Serial No. 403,177.

T 0 all whom it may concern:

Be it known that I, Josnrri F. BIGGS, a citizen of the United States, residing at the city of Richmond, and State of Virginia, have invented certain new and useful Improvements in Amplifiers for Talking Machines, of which the following is a specification, reference being bad to the accompanying drawings.

This invention relates to the art of acoustics and particularly to an improved amplifier for use in connection with a cabinet talking machine wherein ample space is afforded in the rear of the cabinet for housing the amplifier, in such a manner that the rear wall of the amplifier assumes a position in parallelism with the back of the cabinet. It is also to be noted that the forward part of the cabinet affords ample space for an improved combination record rack and ejector as set forth in the co-pending application of Joseph F. Biggs', Serial Number 403,176, filed August 12, 1920.

It is also the aim to provide an amplifier of relatively large proportions whereby the sound waves or vibrations are considerably amplified.

Another object is to provide an amplifier which is of stream line design and connected to the tone arm downwardly from the motor board and curved in order toarch under the motor and deliver the sound mto a chamber at one end of the cabinet.

Still another object is to provide an amplifier of relatively large proportions and of stream line-design as shown with an aim to not only considerably amplify the sound waves but also to produce tones more natural. In attaining this result through extensive tests by means of the stream line design and curved formation of the amplifier it has been found necessary to retard the vibrations or sound ,waves on one of the curved walls of the amplifier relatively to the vibrations on an opposite curved wall. Also in order to accomplish this result it has been found that by providing angular abutments and especially terminating the shorter curved wall in 'a chamber or pocket, that the vibrations or sound waves are retarded.

In the preferred form of the amplifier the shorter curved wall terminates in a'chamher or pocket, thereby not only accomplishing the retardation of the vibrations, but also producing better tones. In another form of the amplifier the short curved wall terminates in an angular portion which also acts to retard the vibrations in order that the vibrations on the shortcurved wall will leave the amplifier at the same time that the vibrations leave the amplifier on the longer curved wall. I

IVhile the design and construction at present illustrated and set forth is deemed pref-' erable, it is obvious that as a result of a reduction of the invention to a more practical form for commercial purposes, the invention may be susceptible of changes, and the right to these changes is claimed, provided theyare comprehended within the scope of what is claimed.

The invention comprises further features and combination of parts, as will be hereinafter set forth, shown in the drawings and claimed.

In the drawings:

Figure 1 is a vertical cross sectional view of a cabinet talking machine showing the improved amplifier as mounted therein showing the chamber or pocket at the end of the short curved wall thereof,

Figure 2 is a longitudinal sectional view on the line 2-2 of Figure 1, also showing the pocket or chamber at the terminus of the short curved wall,

\ Figure 3 is a perspective view of the amplifier shown in Figures 1 and 2.

Figure 4 is a longitudinalsectional view through a cabinet talking machine showing another fornr of amplifier mounted therein, wherein the short curved wall of the amplifier terminates in an angular portion acting .to retard the vibrations and render them more natural.

Figure 5 is a detail perspective view of the amplifier shown in Figure 4.

Referring to the drawings, 1 designates the cabinet of a talking machine which may be any suitable. shape, preferably of an,

elongated rectangular contour or oblong and it is to be noted that the upper part of the cabinet has a chamber 2 for the reproducing mechanism 3 which comprises the record supporting table 4., the sound box 5 and the tone arm 6. The upper part of the cabinet also has another chamber 7 in which the vibrations or sound waves enter, there being a partition 8 separating the two chambers or compartments 2 and 7. Suitable covers or closures 8 and 9 are hingedly mounted on the cabinet to close these chambers or compartments. A motor board 10 supports the usual motor 11 and connected communicatively with the tone arm and extending downwardly from the motor board is the amplifier 12, the outlet end 13 of which communicates with the chamber 7'.

The amplifier 12 is of stream line design relatively narrow and of rectangular shape in cross section and may be constructed of any suitable material preferably wood. The amplifier has its smaller end substantially square in cross section and the relatively small opening 14 registers with the tone arm at the point where the smaller end 15 of the amplifier engages the under face of the motor board. The amplifier also comprises the side walls 16 which are of stream line design from the smaller end of the amplifier to the larger end as shown.

The sides 16 have relatively wide portions 17. The amplifier also comprises the upper curved wall 18, the curvature of which permits of the reception of the motor 11 in the rear of the cabinet. The outlet end of the amplifier is of relatively elongated shape, thereby permitting the vibrations to expand and amplify to a relatively great degree.

It has been found through experimental tests that in using an amplifier of this design, the vibrations on the upper curved wall of the amplifier will reach the outlet end of the amplifier considerably before the vibrations transmitted along the bottom curved wall, therefore, the present invention afi'ords means at the terminal of the upper curved wall to retard the vibrations transmitted along the wall so that the vibrations on all sides of the amplifier particularly the upper and lower walls will reach the outlet end of the amplifier simultaneously. Not

only is it the aim to retard the vibrations or sound waves for the aforesaid purpose, but it is also the aim to pocket the vibrations for the purpose of rendering them more natural.

In order to more definitely describe the construction of the amplifier and to convey the inventors idea along the lines of the experimental tests, the various parts of the amplifier have been designated by reference letters as indicated in Figures 3 and 5. The shape of the amplifier makes it of unusual value as a sound conveyor or transmitter for the reason that it is of stream line design and relatively narrow; that is, compared with the outlet end. F urthermoref the amplifier has the advantage of taking up less room in the cabinet, the great advantage of afiording relatively broad sides tapering from the smaller end of the amplifier and which acts as supports for the sound waves or vibrations.

The amplifier has a contour substantially square in cross section at its smaller end, and as the side walls of the amplifier merge to the larger end, the cross sectional contour of the amplifier becomes oblong or relatively narrow in shape acting to also naturalize the vibrations as they are transmitted. The amplifier as has heretofore been stated may be constructed of any suitable material preferably Wood of any kind and as previously stated, the amplifier is of substantially circular stream line contour or design with the outlet end thereof under the cover of the cabinet whereby the cover may act as a mufller or modifier for governing the volume of sound.

As defined in the copending application, for a patent on a cabinet machine in the name of Joseph F. Big-gs, Serial Number 403,175, filed August 12, 1920, the cover acts to deflect the sound and in so doing acts to modify it. In order to accomplish this, the cover may be arranged in different adjusted positions as in said co-pending application by such means as is shown in such applicatio The upper curved wall 18 at the point where it terminates adjacent thevchamber 7 is curved in a returned direction substantially toward the smaller end of the amplifier as indicated at 20. This curvature of the wall 18 merges into a perpendicular por-' tion 21 which in turn merges into a horizontal portion or wall 22. Rising upwardly from one edge of the wall 22 is a second perpendicular wall 23. It will be noted that the Wall 22 extends in a vertical plane substantially in alignment with the inner curved surface 24 of the wall 18 and since the horizontal wall 2 is directly over the returned curved portion 20 of the wall 18 a suitable chamber or pocket 25 is provided at the terminus of the wall 18. This pocket or chamber 25 acts to materially retard the sound vibrations by pocketing them. Furthermore it has been found that the vibrations in being transmitted along the wall 18 are retarded somewhat before they reach the pocket or chamber 25 owing to the return or abrupt curvature of such wall.

It will be noted that the lower edge of each stream line side designated by the reference character bc-a3ef is of a curved or arcuate shape as is also the upper edge Zk-no. However,' the edges Z-k 72-0 are not concentric with the edges bc-de-f. It would be noted that the upper curved wall 18 terminates in a re turned curved portion as at 20 or in an angular portion as in Figure 5 acting to retard the sound vibrations transmitted along the wall 21 amplifier.

Referring to Figure 5 it will also be noted that the edges Zl o are also not concentric with the edges Z cLe-f. Referring again to Figure 5' it will be noted that parts of the angular portions are designated by reference letters and this part comprises and along the sides of thecarried to the mouth end of the amplifier and on this basis of the law of acoustics, the inventor has developed an amplifier for relatively increasing the amplification of the sound.

It will be noted that the distance bc- /]@f is much longer than the circular line from Zs passing through 0 and 70. After extensive experimental tests it has been found that in producing an amplifier of this character including the shape from Z-k0 terminating in a right angle at 0 with arelatively straight line from. 0- terminat- 4 ing in a right angle from ps forming an inverted right angle at 3), act to retard the upper side of the sound wave so that part of the sound wave on the upper side of the amplifier will not reach the mouth end of the amplifier fg/Ls until the sound wave transmitted alongthe lower curved wall of the amplifier has also reached the mouth end or" the amplifier along the line Z)ccZf. In other words, by the provision of the right angle parts at the terminal of the upper curved wall 18 of the amplifier all sides or alll portions of the sound waves or vibrations will reach the mouth 8nd of the amplifier simultaneously.

It has been found that if an amplifier is straight in fact, all sides of the amplifier uniform in length, the sound waves or vibrations cannot be retarded or interrupted,

but in the case wherethe amplifier has one wall relatively short with regard to an opposite wall it is necessary to retard the vibrations or sound, hence the provision of the right angle portions at terminals of the upper wall 18 of the amplifier, so as to permit the sound waves or vibrations to reach the mouth end of the horn uniformly. Though the wall 18 has but two of the retarding right angle portions at the terminal it is obvious that they may be increased in number or relatively increased or decreased in size, or it has been also found that to corrugate the curved wall 18 in a graduated manner from the smaller end of the amplifier to the terminus of the wall 18, will also act to retard'the sound and graduate it so as to permit the sound vibrations or waves on the wall 18 to reach the mouth'end of the horn at the same time the sound waves 01. vibrations along the lower stream line curved wall :26 reach the month end.

The invention having been set forth, what is claimed as new and useful is:

1. In an amplifier, an amplifier body having inlet and outlet ends assuming positions substantially on the same plane, said body being of semi-circular form and of stream line taper, whereby the body gradually increases in cross sectional area from the smaller end of the amplifier body to the outlet end thereof, said amplifier body having an upper arcuate form wall for the transmission of vibrations, said body having an opposite arcuate wall constructed on a greater radius than the first arcuate wall, sound vibrating side walls arranged in di-- verging directions from the inlet end of the amplifier body to the outlet end and connecting said arcuate walls, and means atthe top of the outlet end and formed at the terminus of the wall of less radius to synchronize the vibrations with those transmitted along the wall having a greater radius.

2. A sound amplifier comprising an upper arcuate form wall for transmission of vibrations, an opposite wall of arcuate form constructed on a greater radius than the up per wall, sound vibratin side walls disposed in diverging directions trom the smaller end of the amplifier to the outlet end thereof and connecting said opposed arcuate walls, and means constructed, in the upper arcuate wall adjacent the outlet end for retarding and synchronizing the vibrations with those which are transmitted along the arcuate wall of greater radius, whereby all vibrations may reach the outlet end of the amplifier simultaneously.

3. A sound amplifier comprising an amplifier body, of stream line taper from the smaller end of the amplifier to the larger discharging end thereof, said body having opposed arcuate form walls of difierent curvatures and constructed upon different radii eccentrically disposed, one of said walls being of greater length than the other, sound vibrating side walls disposed in diverging directions and connecting said opposite arcuate walls, whereby said body gradually increases in cross sectional area from the smaller end of the amplifier to the discharging mouth end thereof. the shorter arcuate wall terminating in an abrupt curvature adjacent the discharging mouth end, said abrupt curvature terminating in a plurality of angular ofi'sets acting'to synchronize the sound vibrations, whereby they may reach. the month end of the amplifier at the same time the vibrations. which are transmitted along the arcuate wall of greater length, reach the month end of the ampifier.

4. An amplifier comprising a hollow body having .inlet and outlet extremities, said body tapering in stream line arcuate form from the inlet extremity to the outlet extremity said amplifier having opposed an cuate form vibrating walls, one having a larger curve than the other, and means constructed in the vibrating wall of smaller curve 'for synchronizing the sound vibrations, whereby they may reach the outlet extremity at the same time the vibrations, which are transmitted along the vibrating wall of the larger curve, reach the outlet extremity.

5. An amplifier comprising a body relatively small at one end and gradually increasing in cross sectional area from said end to and terminating in an outlet end, said body having opposite arcuate sound vibrating walls, one of greater radius than the other, the vibrating wall of less radius having, a plurality of right angle bafiies acting to retard the vibrations, whereby they Will reach the outlet end at the same. time the vibrations, which are transmitted along the arcuate wall of greater radius, reach the outlet end.

6. An amplifier comprising an amplifier body relatively small at one end and having a curvature of stream line contour, and gradually increasing in cross sectional area from the smaller end to and terminating in an outlet end, said ends assuming positions substantially on the same plane, and means constructed in oneot the walls of the amplifier body adjacent the outlet endJ-forsynchronizing the sound vibrations, whereby said vibrations transmitted along two of said curved walls of the body may reach the outlet end of the amplifier simultaneously '7. An amplifier comprising an amplifier body having a pair of opposed walls of different arcuate shape constructed upon-different radii eccentrically arranged, a pair of opposite vibrating fiat side walls disposed in diverging directions from one end toward and to the opposite end andconnected to said arcuate opposed walls, whereby the amplifier gradually increases in cross sectional area from one end to the other, the shorter of said arcuate opposed vibrating walls terminating at one end in an abrupt curvature having a return curved portion terminating in means for synchronizing the sound vibrations, whereby the sound vibrations of both arcuate walls will reach the outlet end of the amplifier simultaneously.

8. An amplifier having inlet and outlet extremities, the latter larger than the former, said amplifier having opposed vibrating arcuate walls, one constructed on a greater 1 adjacent the outlet end for synchronizing the vibrations.

10. An amplifier comprising a body provided with inlet and outlet extremities, said body having opposed vibrating Walls of semicircular contour and positioned eccentrically with each other, one constructed on a smaller radius than the other, and means formed in the wall of smaller radius and adjacent the upper portion of said outlet extremity, to retard the vibrations along the wall of smaller radius, whereby they may synchronize with the vibrations passing along the wall of greater radius, enabling all vibrations to leave the outlet extremity simultaneously.

In testimony'whereof I hereunto afiix my signature.

JOSEPH F. Blues. 

